EP0056659B1 - Appareil de régulation de convertisseur pour système à courant continu ayant des stations multiples connectées en parallèle - Google Patents

Appareil de régulation de convertisseur pour système à courant continu ayant des stations multiples connectées en parallèle Download PDF

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Publication number
EP0056659B1
EP0056659B1 EP19820100419 EP82100419A EP0056659B1 EP 0056659 B1 EP0056659 B1 EP 0056659B1 EP 19820100419 EP19820100419 EP 19820100419 EP 82100419 A EP82100419 A EP 82100419A EP 0056659 B1 EP0056659 B1 EP 0056659B1
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EP
European Patent Office
Prior art keywords
converter
current
voltage
adder circuit
output
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EP19820100419
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German (de)
English (en)
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EP0056659A1 (fr
Inventor
Takeichi Sakurai
Kiyoshi Goto
Hiroo Konishi
Tadao Kawai
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Hitachi Ltd
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Hitachi Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Definitions

  • This invention relates to a converter control apparatus for a parallel connected multi-terminal direct current system wherein at least three or more converters are connected in parallel by common direct current transmission lines.
  • the control apparatus of a converter for direct current power transmission is usually constructed so that it bestows a control pulse on the converter in correspondence with the difference between a current reference value for the constant current control and an actual transmission line current.
  • a signal for reducing the reference value by a certain value called the current margin is bestowed on the control apparatus of the converter which is to be operated as an inverter.
  • the current of the direct current transmission line is determined by a rectifier, while the voltage is determined by the inverter.
  • a stable running is executed.
  • Canadian Patent No. 1033808 (Swedish Patent No. 7512302) has proposed a control system in which each of plural converters is controlled by a control apparatus which can selectively apply either the constant current control or the constant voltage control.
  • the control system of the Canadian patent 10 33 808 is very useful for the operation of a parallel connected multi-terminal direct current system. But the system is not fully satisfactory, for example, when one converter operating as an inverter is removed from the direct current system by chance for some reasons. In this case, the D.C. current supplied by the converters operating as rectifiers flows into other converters operating as inverters through a direct current transmission line. The inverting converters, therefore, are operated under an over current. Such status is most severe where the removed converter was operated as an inverter and as a direct current transmission line voltage control converter.
  • the control apparatus of this invention is contrived in that said apparatus comprises: a first constant current control means which provides a first signal for controlling the current of the converter on the basis of a deviation between a first current reference signal of said converter and the actual current thereof, first and second constant voltage control means which provide third and fourth signals for controlling the voltage of said converter on the basis of a deviation between a voltage reference signal of said converter and the actual voltage thereof, first selector means for selecting the larger one between said first signal of said first constant current control means and the third signal of said first constant voltage control means, second selector means for selecting the smaller one between the signal selected by said first means and the fourth signal of said second constant voltage control means; the control apparatus further comprises a second constant current control means for providing a second signal for controlling the current of the converter on the basis of the deviation between a second current reference signal of said converter and the actual current thereof, third selector means for selecting the larger one between said second signal of said second constant current control means and the fourth signal of the second constant voltage control means, and the fourth
  • the current reference signals to be fed to the first constant current control units of the respective converters are so set that the sum of the current reference signal values of rectifiers among the converters is greater by a certain value (called “the current margin”) than the sum of the current reference signal values of inverters among the converters.
  • Each of the current reference signals to be fed to the second constant current control units of the respective converters is so set that the current reference signal value is the allowable maximum current value of operation of the respective converters.
  • a correcting signal is applied to the control apparatus of the converter for determining the voltage of the direct current system so that the voltage reference signal value may decrease by a certain value (termed "the voltage margin").
  • the optimum one is selected by two maximum value selector circuits as well as a minimum value selector circuit and is delivered as an output.
  • Fig. 1 is a block diagram for conceptually explaining the position which the control apparatus of this invention occupies in a direct current system.
  • U 1 , U 2 , U 3 and U 4 denote converter stations, respectively.
  • the converter stations U 1 ⁇ U 4 are connected to respective alternating current systems AC 1 , AC 2 , AC 3 and AC4, and they are connected in parallel by common direct current transmission lines DCp and DC " .
  • DCp and DC " common direct current transmission lines
  • Each converter station U is provided with a transformer Tr, a converter CON, the control apparatus CA of this invention, and a current detector CT and a voltage detector PT for detecting a current through the converter CON and a terminal voltage of the converter CON, respectively.
  • the transformer Tr couples the alternating current system AC and the converter CON
  • the converter CON is connected to the direct current transmission lines DCp and DC " .
  • a centralized control device CC is disposed.
  • the control apparatus CA of each converter station U develops a control signal for the corresponding converter CON on the basis of current and voltage signals I d and E d respectively given as outputs of the current detector CT and the voltage detector PT, current and voltage reference signals I dp and E dp given from the centralized control device CC, and signals on the necessity for the bestowal of a current margin Old and a voltage margin ⁇ E d , and it delivers an ignition pulse to the converter CON at a control angle a responsive to the control signal.
  • Each control apparatus CA includes two constant current control units ACR and a constant voltage control unit AVR as its constituents, and outputs of the units are selectively used.
  • Fig. 2 is a block diagram which shows an embodiment of the essential portions of the control apparatus of this invention.
  • numerals 10, 20, 50, 60, 70 and 130 designate adder circuits. Each of the adder circuits performs the addition of signals which are given in polarities indicated by the signs + and - in the figure.
  • Numerals 40 and 80 represent selector switches.
  • a movable piece 43 of the switch 40 is connected to either a terminal 41 or a terminal 42.
  • a movable piece 83 of the switch 80 is connected to either a terminal 81 or a terminal 82 in the control apparatus of only one converter station, whereas it is at the neutral position and is connected to neither of the terminals in the control apparatuses of the other converter stations.
  • Shown at 30, 90, 100 and 140 are operational amplifiers which have gains -k 1 , -k 2 , +k 3 and -k 4 , respectively.
  • Maximum value selector circuits 110 and 150 and a minimum value selector circuit 120 select the maximum value and the minimum value from among input signals applied thereto and provide them as outputs, respectively.
  • the comparisons are made of magnitudes with the polarities taken into consideration. For example, when -10 V and 0 V are compared, 0 V is judged to be greater.
  • the components denoted by the numerals 10-40 constitute the first constant current control unit ACR n1 (Here, n is a suffix which generally designates the converter stations U l -U 4 .
  • the components denoted by the numeral 130-140 constitute the second constant current control unit ACR n2
  • the components indicated by the numerals 50-100 constitute the constant voltage control unit AVR.
  • a signal produced by the first constant current control unit ACR n1 and one signal produced by the constant voltage control unit AVR are introduced into the maximum value selector circuit 110, from which only the greater signal is provided as an output.
  • a signal produced by the second constant current control unit ACR n2 and another signal produced by the constant voltage control unit AVR are introduced into the maximum value selector circuit 150, from which only the great signal is provided as an output.
  • the signal selected by the maximum value selector circuit 110 and the signal selected by the maximum value selector circuit 150 are introduced into the minimum value selector circuit 120, from which only the smaller signal is provided as an output.
  • the output signal E c of the minimum value selector circuit 120 is introduced into a pulse phase control circuit (not shown) to be described later, so that the ignition pulse of the phase corresponding to the signal E c is bestowed on the converter CON.
  • the current reference signal I dpn1 to flow through the converter CON is fed to the adder circuit 10.
  • the switch 40 has the movable piece 43 thrown on the side of the terminal 41 in the control apparatus of one or all of the converters which are operated as inverters.
  • the movable piece 43 is thrown on the side of the terminal 42 in the control apparatus of any of the converters which are operated as rectifiers.
  • the current margin ⁇ I d is bestowed on the adder circuit 10.
  • I dpn I dpm '.
  • the actual current I dn detected by the current detector CT is introduced into the adder circuit 20.
  • An output of the adder circuit 20 is introduced into the operational amplifier 30.
  • the constant current control unit ACR n1 corrects the current reference signal I dpn1 to the corrected current reference signal I dpn1 ' reduced by the current margin Old and develops the signal corresponding to the deviation from the real current I dn .
  • I dpn1 I dpn1 '. and the signal corresponding to the deviation between the current reference signal I d p n1 and the actual current signal Idn is derived.
  • the current reference signal I dpn2 to flow through the converter CON is fed to the adder 130.
  • the actual current I dn detected by the current detector CT is introduced into the adder circuit 130.
  • An output of the adder circuit 130 is introduced into the operational amplifier 140.
  • the current reference signal I dpn1 in the ACR n1 means the required current under the normal operation, while the current reference signal l d p n2 in the ACR n2 means the maximum allowable current when one converter operating as the inverter is removed from the direct current system.
  • the voltage reference signal E d p at the operation of the converter is fed to the adder circuit 50.
  • E dn of the real terminal voltage of the converter is applied to the adder circuit 50.
  • E dn is provided from the adder circuit 50 as an output.
  • the absolute value is herein employed in order to derive the terminal voltage of the converter as a voltage of the direct current system.
  • the switch 80 has the movable piece 83 thrown onto the side of the terminal 81 or 82 when the converter of the converter station to which the particular switch belongs is to operate as the converter for determining the voltage of the direct current system.
  • the movable piece 83 is placed at the neutral position.
  • the rectifier is made the converter for determining the voltage
  • the movable piece 83 is thrown onto the terminal 81 side
  • the inverter is to determine the voltage
  • the movable piece 83 is thrown onto the terminal 82 side.
  • either of the adders 60 and 70 receives the voltage margin ⁇ E d besides the aforementioned deviation signal E d p-
  • An output of the adder circuit 60 is introduced into the operational amplifier 90; and an output of the adder circuit 70 into the operational amplifier 100. That is, the constant voltage control unit AVR effects the control so that, whether the converter is to operate as the rectifier or as the inverter, it may function as the converter for determining the voltage of the direct current system by the bestowal of the voltage margin.
  • control apparatus CA is additionally provided with a constant extinction angle control unit AyR in order to prevent the inverter from causing commutation failure due to an insufficient extinction angle.
  • the constant extinction angle control unit AyR should be disposed in consideration of the voltage lowering of the alternating current system.
  • the angle a and the voltage E c are linearly proportional in the range in which the control voltage E c is not larger than a value E co and is not smaller than a value E co ', and the angle a does not increase and decrease above 160° and 4° when the values E co and E co ' are exceeded, that is, the angle a is saturated at 160° and 4°.
  • the phase shifter circuit having such E c -versus- ⁇ characteristic is very common, and it will be unnecessary to especially mention an example of a concrete circuit arrangement thereof.
  • the converter is operated as the rectifier in the range of 4° ⁇ a ⁇ 90° and as the inverter in the range of 90° ⁇ a ⁇ 160°.
  • the phase shifter circuit any desired one can be adopted in dependence on the form in which the control voltage E c is derived. It is natural that the characteristic in Fig. 3 is not restrictive.
  • Figs. 4 and 5 are characteristic diagrams for elucidating cases where the direct current system is operated in two different patterns under normal operation by the control apparatus of this invention.
  • stable runnings are conducted at points a, b, c and d.
  • the converter station U 1 and U 2 are operated as rectifier stations [REC] and the converter station U 3 and U 4 as inverter stations [INV].
  • the cases differ in that, while the example in Fig. 4 determines the voltage of the direct current system by the converter station U 1 , the example in Fig. 5 determines it by the converter station U 3 .
  • I dp11 -I dp41 and I dp12 -I dp42 indicate the first and second current reference values of the respective converters, and I d1 -I d4 the actually- flowing current values.
  • E d p indicates the voltage reference value of each converter, and E d1 or E d3 the actual voltage value of the direct current system.
  • DI d and ⁇ E d correspond to the current margin and the voltage margin explained with reference to Fig. 2, respectively.
  • Fig. 4 The example of Fig. 4 is so constructed that the converter station U, determines the voltage of the direct current system. Accordingly, the constant voltage control unit AVR of the control apparatus CA has the movable piece 83 of the switch 80 thrown to the terminal 81 in only the control apparatus CA, of the converter station U 1 , while the movable piece 83 is at the neutral position in the unit AVR of each of the other control apparatuses CA 2 ⁇ CA 4 . In other words, the voltage margin AE d is bestowed only on the adder circuit 60 of the control apparatus CA 1 . Since, as previously stated, the current margin Aid is given in only the control apparatus CA 3 of the inverter station U 3 , the current margin Aid is bestowed only on the adder circuit 10 of the control apparatus CA 3 .
  • the first current reference values I dpn1 are naturally made so that the sum between the current reference values of the rectifiers is equal to the sum between the current reference values of the inverters with the current margin left out of consideration.
  • the first current reference values I dpn1 are naturally made so that the sum between the current reference values of the rectifiers is equal to the sum between the current reference values of the inverters with the current margin left out of consideration.
  • the points a, b, c and d provide the stable running. It is now assumed for the explanation that, likewise to a well-known 1-to-1 direct current system, the direct current system provided with the control apparatuses of this invention has the group of rectifier stations and the group of inverter stations started by a suitable method, and that the voltages and currents of the direct current system reach the points in Fig. 4. The retarded control angles a of the respective converters will be described together with the fact that the points are the stable ones.
  • the operational amplifier 90 receives an input in the linear region in which the input and output are proportional, and the output of the operational amplifier 90 becomes a value corresponding to the error voltage ⁇ 1 .
  • the output of the operational amplifier 90 is selected by the maximum value selector circuit 110 and is provided therefrom. Since the adder circuit 70 has no additive signal, it delivers therefrom a large positive signal corresponding to the voltage margin ⁇ E d having appeared in the adder circuit 50. Therefore, the output of the operational amplifier 100 becomes positively saturated.
  • the second current reference value I dp12 is larger than the first current reference value I dp11 , so that a larger positive signal than the output of the adder circuit 20 appears in the adder circuit 130. Consequently, the output of the operational amplifier 140 becomes negatively saturated.
  • the output of the operational amplifier 100 is selected by the maximum value selector circuit 150 and is provided therefrom.
  • the minimum value selector circuit 120 selects the output of the operational amplifier 90 and delivers it as the output control signal E c .
  • the output at the operational amplifier 90 of the constant voltage control unit AVR 1 is obtained as the control signal E ca , and a gate signal of a retarded control angle ⁇ a is impressed on the converter by the phase shifter circuit not shown. Accordingly, when a voltage fluctuation in the direct current system arises the control apparatus CA 1 absorbs it and controls the voltage of the direct current system so as to normally become E dl , whereas the control apparatus CA 1 effects quite no control as to a fluctuation of the current I d1 .
  • the control apparatus CA 2 of the converter CON 2 which is also the rectifier functions as follows.
  • the current I d2 substantially equal to the first current reference value I d p 21 flows, and hence, the output of the adder circuit 20 becomes a small error voltage ⁇ 2 .
  • the operational amplifier 30 receives an input in the linear region in which the input and output are proportional, and its output becomes a value corresponding to the error voltage ⁇ 2 .
  • the adder circuits 60 and 70 have no additive signal, and hence, the signal corresponding to the voltage margin ⁇ E d as obtained at the adder circuit 50 is applied to the operational amplifiers 90 and 100 without any change, so that the operational amplifiers deliver signals negatively and positively saturated.
  • the output of the operational amplifier 140 becomes negatively saturated in the ACR 22 .
  • the output of the operational amplifier 100 therefore is selected by the circuit 150.
  • the output of the operational amplifier 30 is derived through the maximum value selector circuit 110 as well as the minimum value selector circuit 120. That is, the rectifier CON 2 is subjected to the constant current control by the constant current control unit ACR 21 .
  • the control signal E Cb and the retarded control angle a b at this time are indicated in Fig. 6.
  • the constant voltage control units AVR of the respective control apparatuses CA 3 and CA 4 are similar to the constant voltage control unit AVR 2 of the control apparatus CA 2 , and the operational amplifiers 90 and 100 provide the outputs saturated negatively and positively, respectively.
  • the second current reference values I dp32 and I dp42 are larger than the first current reference values I d p 31 and I dp41 , so that the larger positive signals than the outputs of the adder circuit 20 appears in the adder circuit 130.
  • the outputs of the operational amplifiers 140 therefore, becomes negatively saturated and the outputs of the operational amplifiers 100 are selected by the maximum value selector circuits 150.
  • the operating points a, b, c and d in Fig. 4 are the stable points. It is assumed by way of example that the voltage of the direct current system has lowered very slightly due to any cause. On account of the lowering, the output of the adder circuit 60 increases slightly in the constant voltage control unit AVR 1 of the control apparatus CA 1 . As the result, the output of the operational amplifier 90 decreases correspondingly. This means the decrease of the control voltage E c , so that the retarded control angle decreases and that the voltage of the direct current system is recovered. Regarding the constant voltage control units AVR 2 ⁇ AVR 4 of the other converters, the saturation states of the operational amplifiers 90 and 100 are hardly affected by the slight voltage lowering.
  • these converters are controlled by the constant current control units ACR 21 ⁇ ACR 41 as previously stated. Since the operational ampifier 30 of the constant current control unit ACR 11 of the converter CON 1 is held saturated, the voltage lowering exerts quite no influence on the control unit ACR 11 . The same applies to a change of the current. It is assumed by way of example that the current flowing through the converter CON 2 has increased or decreased very slightly due to any cause. This signifies that very slight current fluctuations of increase or decrease have also arisen in the other converters. As the result, the outputs of the adder circuits 20 of the constant current control units ACR 21 ⁇ ACR 41 of the converters CON 2 ⁇ CON 4 fluctuate very slightly by those components and change the control voltages E c . Eventually, the voltages and currents are stably settled to the points a, b, c and d in Fig. 4.
  • the movable piece 83 of the switch 80 of the constant voltage control unit AVR 3 of the control apparatus CA 3 is connected from the neutral position to the terminal 82. It is also necessary to shift to the neutral position the movable piece 83 of the switch 80 of the constant voltage control system AVR, in the control apparatus CA,. No other manipulation is required.
  • the operational amplifier 100 receives an input in the linear region in which the input and output are proportional, and its output becomes a value corresponding to the error voltage ⁇ 3 '.
  • the voltage margin ⁇ E d having been applied to the adder circuit 60 is removed, so that the output of the adder circuit 60 becomes a large positive one.
  • the output of the operational amplifier 90 is, therefore, saturated negatively.
  • the operational amplifier 30 had been negatively saturated and the operational amplifier 100 had been positively saturated. Therefore, when the output of the operational amplifier 90 is also saturated negatively, the negative saturation value of the operational amplifier 30 or 90 is provided as an output from the maximum value selector circuit 110 and it passes through the minimum value selector circuit 120.
  • the control signal E c which renders the retarded control angle a zero is produced from the control apparatus CA 1 of the converter CON,.
  • the current I d1 of the converter CON 1 therefore increases. This increase continues until the current I d1 becomes a value I d1 ' which is substantially equal to the current reference value I dp1 .
  • the error voltage of the adder circuit 20 of the control apparatus CA 1 becomes a small value ⁇ 1 ' and the output of the operational amplifier 30 becomes a value corresponding to the error voltage ⁇ 1 ', the current increase comes to a stop.
  • the saturated status of the operational amplifier 140 does not change since the reference value I d p 32 is larger than the direct current I d1 flowing through the converter CON 1 .
  • the output of the amplifier 140 therefore, is saturated negatively.
  • the converter CON 1 merely has the voltage margin ⁇ E d removed therefrom, and the control by the constant voltage control unit AVR 1 is shifted to the control by the constant current control unit ACR 11 .
  • the current through the converter CON 1 increases by approximately the current margin ⁇ I d . Since, however, the control apparatuses CA 2 and CA 4 of the respective converters CON 2 and CON 4 are subject to no manipulation, they still effect the constant current control function. Therefore, the current increased by the converter CON 1 exerts eventually no influence on the converters CON 2 and CON 4 even though it tries to affect them, and it cannot help flowing into the converter CON3.
  • the control apparatus CA 3 accordingly, a negatively large error voltage appears at the adder circuit 20, with the result that the output of the operational amplifier 30 is positively saturated.
  • the output of the operational amplifier 100 is selected by the maximum value selector circuit 150 and the minimum value selector circuit 120. That is, merely by the addition of the voltage margin ⁇ E d , the converter CON3 is changed from the control by the constant current control unit ACR 3 , to the control by the constant voltage control unit AVR 3 .
  • Fig. 5 The characteristic at this time is illustrated in Fig. 5.
  • the relation between the control voltage E c and the retarded control angle a of each control apparatus is illustrated in Fig. 7, the quantities being dashed.
  • Fig. 5 the stable running points are indicated at a, b, c and d. It is understood that the converters CON 1 , CON 2 and CON 4 are subject to the constant current control, while the converter CON3 is subject to the constant voltage control.
  • the respective constant current control units ACR 12 ⁇ ACR 42 do not take part in control operation of the direct current transmission system.
  • the constant extinction angle control unit AyR is naturally provided additionally.
  • the constant extinction angle control unit AyR any desired one can be adopted.
  • the unit AyR shall provide a voltage as an output on the basis of the current I dn flowing through the inverter CONN and an a.c. voltage E an applied to the inverter CONn, the output voltage corresponding to the maximum retarded control angle ⁇ max at which the inverter does not undergo the commutation failure under the current and the voltage.
  • the output of the constant extinction angle control unit AyR is fed to the minimum value selector circuit 120.
  • the constant current control unit ACR or the constant voltage control unit AVR provides an output voltage greater than the output of the constant extinction angle control unit AyR and intends to deliver an ignition pulse at a larger retarded control angle in order to maintain the current or voltage of the converter, then the output of the constant extinction angle control unit AyR will be selected and the control which prefers the stable running of the inverter rather than the maintenance of the current or voltage will be established.
  • the characteristic curves of the two examples i.e. Figs. 8 and 10 show influences to which the direct current system having been stably operated under the state of Fig. 4 is subject on account of the case in which the converters CON3 and CON 4 operating as the inverters are removed from the direct current system due to any cause.
  • the stable running are eventually attained at points a, b, and d and b and d.
  • the examples involve differences in the current distribution and the voltage of the direct current system.
  • the characteristic curves of the two examples i.e. Figs. 9 and 11 show the influences to which the direct current system having been stably operated under the state of Fig. 5 is subject on account of the case in which the converters CON3 and CON 4 operating as the inverters are removed from the direct current system due to any cause.
  • the stable running is eventually attained at points a, b and d and a, b and c.
  • the examples involves differences in the current distribution and the voltage of the direct current system.
  • the converter operating as the inverter is operated under allowable maximum current not so as to become over current.
  • Fig. 12 is a block diagram which shows another embodiment of the essential portions of the control apparatus of this invention.
  • the same or equivalent parts as in the embodiment of Fig. 2 have the same symbol assigned thereto.
  • all the control apparatuses of the converters are provided with means for bestowing the current margin and the voltage margin, and the margins are bestowed on only the necessary control apparatuses CA by the switches 40 and 80 in response to the command from the centralized control device CC.
  • the control apparatus of Fig. 12 is convenient for the current margin and the voltage margin to be commanded from the centralized control device CC in forms already considered. For this reason, when the apparatus of Fig. 12 is compared with that of Fig.
  • the former differs from the latter in that the gain of the operational amplifier 90 is altered from -k 2 to +k 2 , that a polarity changer 200 is required and that the terminal voltage E dn of the converter need not be derived in the absolute value.
  • both the apparatuses are substantially the same.
  • the reference values of the current and the voltage are given as follows.
  • the current setpoint with the current margin considered is bestowed on the control apparatus of one or all of the converters which are operated as inverters. That is, the corrected current reference value I dpn1 ' indicated in Fig. 2 is bestowed.
  • the voltage reference value E d p-AE d with the voltage margin considered is bestowed only on the control apparatus of one converter which is operated as the converter for determining the voltage of the direct current system.
  • the value E d p is given as the voltage reference value.
  • the adder circuit 60 is given the voltage reference value directly, while the adder circuit 70 is given the same through the polarity changer 200.
  • the voltage E dn of the direct current system is directly introduced into the adder circuits 60 and 70.
  • the polarities of the signals in the adder circuits are + and - as indicated in the figure.
  • the direct current system can also be stably operated by the embodiment of Fig. 12.
  • the converter CON will be discussed.
  • the constant current control unit ACR 11 a large error voltage appears at the adder circuit 20, and the operational amplifier 30 is negatively saturated.
  • the error voltage of the adder circuit 60 of the constant voltage control unit AVR 1 is small, and the operational amplifier 90 provides an output in the linear region. Since the adder circuit 70 produces an output of very large positive error voltage, the operational amplifier 100 is positively saturated. As the result, the output of the operational amplifier 90 is selected as the control voltage E c .
  • the constant current control unit ACR 12 of course, a large error voltage appears at the adder circuit 130, and the operational amplifier 140 is negatively saturated.
  • the converter CON is subject to the constant voltage control.
  • the error voltage of the adder circuit 20 of the corresponding one of the constant current control units ACR 21 ⁇ ACR 41 becomes small, and the operational amplifier 30 provides an output in the linear region.
  • the adder circuit 60 provides an output of large negative error voltage
  • the adder circuit 70 an output of large negative error voltage. Therefore, the operational amplifiers 90 and 100 are saturated negatively and positively, respectively.
  • the error voltage of the adder circuit 130 is large, and the operational amplifier 140 is negatively saturated. Consequently, the converters CON 2 ⁇ CON 4 are subject to the constant current control.
  • the converter CON3 which is the inverter and which determines the voltage of the direct current system has the voltage reference value E d p-AE d with the current margin considered.
  • the converter terminal voltage E d3 is given in the negative sign. Accordingly, the error voltage of the adder circuit 70 of the control apparatus CA 3 of the converter CON3 becomes small, and the output of the operational amplifier 100 becomes the linear region. Both the adder circuits 20, 60 and 130 produce large error voltages, and the operational amplifiers 30, 90 and 140 are saturated positively and negatively, respectively. As the result, the output of the operational amplifier 100 is selected as the output of the control voltage E c .
  • the inverter CON3 is subject to the constant voltage control. It is as explained of the state of Fig. 4 that the other converters are subject to the constant current control.
  • the exemption of one converter from the direct current system under operation may be made as follows.
  • the converter CON determining the voltage of the direct current system during the operation in the state of Fig. 4
  • the voltage margin ⁇ E d is shifted to any of the other converters CON 2 ⁇ CON 4 .
  • the state of Fig. 5 is established.
  • the current reference values of the respective converters are reduced without destroying the condition that the difference between the sum (I dp11 +I dp21 ) of the current reference values of the rectifiers and the sum (I dp31 '+I dp41 ) of the corrected current reference values of the inverters is equal to the current margin ⁇ I d .
  • the converter is connected to the direct current system.
  • the voltage is set at the value E d p.
  • the current reference value is increased gradually as the foregoing relation of the current reference values is satisfied.
  • the constant current control units ACR n2 do not take part in control operation of the direct control transmission system.
  • Figs. 13 and 14 show the characteristic diagrams for explaining different states under which the direct current system is operated by the control apparatus of this invention. These diagrams are similar and corresponding to that of Figs. 4 and 5 except that the each voltage margin value ⁇ E d of the control apparatus CA is different each other.
  • Figs. 15 and 16 are characteristic diagrams corresponding to that of Figs. 8 and 10 in case of the converters being operated under characteristic diagrams shown in Figs. 13 and 14.
  • the line voltage is determined by the converter which has the largest voltage margin.
  • the signals responsive to the differences between the current reference values and the actual converter current are produced by the constant current control units ACR n1 and ACR n2 , while the two different signals of the positive and negative directions are produced by the constant voltage control unit on the basis of the voltage reference value with the voltage margin considered and the terminal voltage of the converter. From among the four signals, the most suitable signal is selected by the maximum value selector circuits 110 and 150 as well as the minimum value selector circuit 120. Thus, the converters are controlled so that the direct current system may stably operate in any situation.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Rectifiers (AREA)
  • Direct Current Feeding And Distribution (AREA)

Claims (10)

1. Appareil de commande pour convertisseurs d'un système à courant continu avec des unités montées en parallèle, où au moins trois convertisseurs (CON) sont raccordés en parallèle à des lignes de transmission de courant continu (DCp, DCn), avec
un premier régulateur de courant constant (ACRn1); 10 ... 40), lequel émet un premier signal régulateur du courant du convertisseur (CON) compte tenu de l'écart entre un premier signal de courant de référence (Idpn1) du convertisseur et son courant effectif (ldn),
avec un premier et un deuxième régulateurs de tension constante (AVRn; 50 ... 100), lesquels émettent des troisièmes et quatrièmes signaux régulateurs de la tension du convertisseur (CON) compte tenu de l'écart entre un signal de tension de référence (Edp) du convertisseur et sa tension effective (Edn),
avec un premier dispositif sélecteur (110) pour choisir entre le premier signal du premier régulateur de courant constant (ACRn,) et le troisième signal du premier régulateur de tension constante (60, 90) le signal plus grand, avec un deuxième dispositif sélecteur (120) pour choisir entre le signal choisi par le premier dispositif (110) et le quatrième signal du régulateur de tension constante (70, 100) le signal plus petit,

caractérisé par le fait que l'appareil de commande comporte en outre:
un deuxième régulateur de courant constant (ACR"2) pour faire émettre un deuxième signal pour régler le courant du convertisseur compte tenu de l'écart entre un deuxième signal de courant de référence (Idpn2) du convertisseur (CON) et son courant effectif (ldn), et
un troisième dispositif sélecteur (150) pour choisir entre le deuxième signal du deuxime régulateur de courant constant (ACRn2) et le quatrième signal du deuxième régulateur de tension constante (70, 100), le signal plus grand,
et que le quatrième signal du deuxième dispositif sélecteur (120) est remplacé par le signal de sortie du troisième dispositif sélecteur (150).
2. Appareil de commande pour convertisseurs suivant la revendication 1, caractérisé par
un régulateur d'angle d'effacement constant (AyR), qui émet un signal pour maintenir à une valeur prédéterminée l'angle d'effacement du convertisseur, déterminé par le courant continu (Idn) traversant le convertisseur (CON) et la tension (Ean) d'un système à courant alternatif branché sur le convertisseur, le signal de sortie du régulateur d'angle d'effacement constant étant appliqué au deuxième dispositif sélecteur (120).
3. Appareil de commande pour convertisseurs suivant la revendication 1 ou 2, caractérisée par le fait qu'au moins l'un des premier et deuxième régulateurs de tension constante (60, 90, 70, 100) est conçu de sorte à émettre comme signal de sortie un signal d'excès relatif à la tension effective du convertisseur (CON) concerné, dans un état uniforme.
4. Appareil de commande pour convertisseurs suivant l'une quelconque des revendications 1 à 3, caractérisé par le fait qu'il est prévu un dispositif pour régler le premier signal de courant de référence (Idpn1) des appareils de commande de tous les convertisseurs qui forment le système à courant continu, de sorte qu'une somme des courants de référence des convertisseurs fonctionnant en redresseurs peut être plus grande d'une valeur déterminée que la somme des courants de référence corrigées des convertisseurs travaillant comme onduleurs.
5. Appareil de commande pour convertisseurs suivant l'une quelconque des revendications 1 à 4, caractérisé par le fait qu'il est prévu un dispositif pour faire attribuer aux deuxièmes signaux de courant de référence (IdPn2) une valeur supérieure à celle des premiers signaux de courant de référence (Idpn1).
6. Appareil de commande pour convertisseurs suivant l'une quelconque des revendications 1 à 5, caractérisé par un dispositif pour régler la tension de référence (EdP) à une valeur sensiblement plus petite que les valeurs de tension de référence de l'autre convertisseur du système à courant continu.
7. Appareil de commande pour convertisseurs suivant la revendication 6, caractérisé par le fait qu'il est prévu un dispositif pour appliquer une tension de référence inférieure d'une valeur prédéterminée aux valeurs de tension de référence des autres appareils de commande pour convertisseurs.
8. Appareil de commande pour convertisseurs suivant l'une quelconque des revendications 1 à 7, caractérisé par le fait que le premier régulateur de courant constant (ACRn1) comprend un premier circuit de sommation (10) qui reçoit la première valeur de courant de référence (Idpn1) du convertisseur (CON) comme signal d'entrée, et un deuxième circuit de sommation (20) qui reçoit le signal de sortie du premier circuit (10) et la valeur de courant effective (Idn) du convertisseur comme signaux d'entrée, et qui émet comme signal de sortie la différence entre ces signaux d'entrée, ainsi qu'un premier amplificateur opérationnel (30) qui amplifie le signal de sortie du deuxième circuit de sommation (20) à l'aide d'un facteur d'amplification donné,
et que le deuxième régulateur de courant constant (ACRn2) comporte un troisième circuit de sommation (130) qui reçoit la deuxième valeur de courant de référence (Idpn2) du convertisseur (CON) et le courant effectif (ldn) du convertisseur comme signaux d'entrée et émet comme signal de sortie la différence entre ces signaux d'entrée, et un deuxième amplificateur opérationnel (140) qui amplifie le signal de sortie du troisième circuit de sommation (130) à l'aide d'un facteur d'amplification donné, et que le premier et le deuxième régulateurs de tension constante (AVRn) présentent:
un quatrième circuit de sommation (50) qui reçoit la valeur de tension de référence (Edp) du convertisseur et sa valeur effective (Edn) comme signaux d'entrée et émet comme signal de sortie la différence entre ces signaux d'entrée,
un cinquième circuit de sommation (60) qui reçoit le signal de sortie du quatrième circuit de sommation (50) comme signal d'entrée,
un troisième amplificateur opérationnel (90) qui amplifie le signal de sortie du cinquième circuit de sommation (60) à l'aide d'un facteur d'amplification donné, un sixième circuit de sommation (70) qui reçoit comme signal d'entrée le signal de sortie du quatrième circuit de sommation, et
un quatrième amplificateur opérationnel (100) qui amplifie le signal de sortie du sixième circuit de sommation à l'aide d'un facteur d'amplification donné,
et que le premier dispositif sélecteur (110) choisit l'un des signaux de sortie du premier et du troisième amplificateurs (30, 90),
et que le deuxième dispositif sélecteur (120) choisit l'un des signaux de sortie du premier et du deuxième dispositifs sélecteurs (110, 150),
et que le troisième dispositif sélecteur (150) choisit le signal plus grand parmi les signaux de sortie du deuxième et du quatrième amplificateurs opérationnels (100, 140),
et qu'il est prévu un dispositif pour appliquer un signal (Ald) au premier circuit de sommation (20) de l'appareil de commande du ou des convertisseurs (CON) qui, parmi tous les convertisseurs constituant le système à courant continu, fonctionnent comme inverseurs, pour faire baisser sensiblement le courant de référence (ldpn1), et qu'il est prévu un dispositif pour appliquer un signal (ΔEd) à ce cinquième circuit de sommation (60) de l'appareil de commande de celui de tous les convertisseurs (CON) constituant le système à courant continu pour faire baisser sensiblement le signal de sortie du quatrième circuit de sommation (50), si ledit convertisseur travaille comme redresseur, et pour appliquer ledit signal au sixème circuit de sommation (70) si ce convertisseur fonctionne en onduleur.
9. Appareil de commande pour convertisseurs suivant la revendication 8, caractérisé par le fait qu'il est prévu un interrupteur (80) pour faire appliquer le signal (ΔEd) au cinquième ou au sixème circuits de sommation (60, 70), cet interrupteur se prêtant au fonctionnement sélectif.
10. Appareil de commande pour convertisseurs suivant l'une quelconque des revendications 1 à 7, caractérisé par le fait que le premier régulateur de courant constant (ACRn1) comprend un premier circuit de sommation (20) qui reçoit une première valeur de courant de référence (Idpn1') du convertisseur (CON) et sa valeur effective (Idn) comme signaux d'entrée et émet comme signal de sortie la différence entre ces signaux d'entrée, et qui comprend un amplificateur opérationnel (30) qui amplifie le signal de sortie du premier circuit de sommation (20) à l'aide d'un facteur d'amplification donné,
et que le deuxième régulateur de courant constant (ACR"2) prévu pour le convertisseur (CON) fonctionnant en inverseur, comprend un deuxième circuit de sommation (130) qui reçoit une deuxième valeur de courant de référence (Iapn2) du convertisseur et sa valeur effective (Idn) comme signaux d'entrée et émet comme signal de sortie la différence entre ces signaux d'entrée, et présente un deuxième amplificateur opérationnel (140) qui amplifie le signal de sortie du deuxième circuit de sommation à l'aide d'un facteur d'amplification donné,
et que le régulateur de tension constante (AVR) comporte un troisième circuit de sommation (60) qui reçoit comme signaux d'entrée la valeur de tension de référence (Edp―ΔEd) du convertisseur (CON) et sa valeur effective (Edn) et émet comme signal de sortie la différence entre ces signaux d'entrée, et comprend un troisième amplificateur opérationnel (90) qui amplifie le signal de sortie du troisième circuit de sommation à l'aide d'un facteur d'amplification donné, ainsi qu'un quatrième circuit de sommation (70) qui reçoit comme signaux d'entrée un signal représentant la valeur de tension de référence à signe contraire de ce convertisseur et la valeur de tension effective de ce convertisseur et émet comme signal de sortie la différence entre ces signaux d'entrée, et un quatrième amplificateur opérationnel (100) qui amplifie le signal de sortie du quatrième circuit de sommation à l'aide d'un facteur d'amplification donné,
et que le premier dispositif sélecteur (110) choisit l'un des deux signaux de sortie du premier et du troisième amplificateurs opérationnels (30, 90),
et que le deuxième dispositif sélecteur (120) choisit l'un des deux signaux de sortie du premier et du troisième dispositifs sélecteurs (110, 150),
et que le troisième dispositif sélecteur (150) choisit l'un des signaux de sortie du deuxième et du quatrième amplificateurs opérationnels (100, 140),
et qu'il est prévu un dispositif pour régler les premières valeurs de courant de référence (Idpn1') de ces convertisseurs (CON) de sorte que la somme des valeurs de courant de référence de tous les redresseurs des convertisseurs qui forment le système à courant continu, puisse être supérieure d'une valeur donnée à la somme des valeurs de courant de référence de tous les onduleurs, et qu'il est prévu un dispositif pour régler les deuxièmes valeurs de courant de référence (ldpn2) sur une valeur supérieure à la première valeur de courant de référence (Idpn1),
et qu'il est prévu un dispositif pour régler la valeur de tension de référence (Edp~-ΔEd) de l'un de tous les convertisseurs (CON) du système à courant continu sur une valeur inférieure aux valeurs de tension de référence des autres convertisseurs.
EP19820100419 1981-01-21 1982-01-21 Appareil de régulation de convertisseur pour système à courant continu ayant des stations multiples connectées en parallèle Expired EP0056659B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP633081A JPS57122630A (en) 1981-01-21 1981-01-21 Control device for parallel multiterminal dc transmission converter
JP6330/81 1981-01-21

Publications (2)

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EP0056659A1 EP0056659A1 (fr) 1982-07-28
EP0056659B1 true EP0056659B1 (fr) 1985-09-25

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US (1) US4441032A (fr)
EP (1) EP0056659B1 (fr)
JP (1) JPS57122630A (fr)
CA (1) CA1171904A (fr)
DE (1) DE3266451D1 (fr)

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CN104537158B (zh) * 2014-12-12 2017-11-14 上海交通大学 适用于vsc‑hvdc***的建模方法及同步样机

Also Published As

Publication number Publication date
EP0056659A1 (fr) 1982-07-28
CA1171904A (fr) 1984-07-31
JPS57122630A (en) 1982-07-30
US4441032A (en) 1984-04-03
DE3266451D1 (en) 1985-10-31
JPH0254012B2 (fr) 1990-11-20

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